This invention relates to insulated window panes. More particularly, it refers to a method of forming two or more impact resistant laminated insulating window panes and mounting them in a window frame.
Although multiple glazed insulating glass mounted in a frame is well known as shown in U.S. Pat. Nos. 3,553,913; 4,542,611; 4,822,649; 5,156,894; 5,269,108 and 5,878,538. Such patents do not describe making impact resistant window panes and mounting them in a frame. Insulating glass having substantial structural resistance to wind loading stresses is described in U.S. Pat. No. 5,714,214. Glass resistant to impact from large missiles, as described in the South Florida Building Code, is not described in this patent.
Recently, local building codes have specified the need for impact resistant glass, the glass to withstand up to nine pounds of force from a 2xc3x974 board shot at the glass at up to 50 feet/second. The prior art does not provide a method for mounting such impact resistant glass in a window frame.
The method of this invention balances large missile impact resistance and thermal efficiency in a window system. A pair of impact resistant glass panes in a customary dry-lamination process are formed by coating the glass with a plurality of plies of safety film laminated together. A spacer is positioned to separate each coated glass pane. A top or inboard surface of the spacer is positioned level with a top of the window frame along a site line. An area from the bottom or outboard portion of the spacer to an edge of the glass is back-filled with silicone sealant or buytal. The spacer is xc2xc to xc2xe inch in width between the glass panes. The resulting impact resistant two window pane composite is secured into a glazing channel on a window frame with silicone applied in the glazing channel between an inner surface of the window frame and a surface of the window glass panes opposite the coated surface.